BP said it had to cut the value of its US shale gas assets and a number of its refineries.

It said its profits were also reduced by the decision to suspend its Liberty offshore oil project in Alaska.

Even without these one-off factors, BP's profit was lower as it was hit by weaker global oil prices and the reduced price of natural gas in the US.

In addition, it said that planned maintenance had cut production in the Gulf of Mexico, and that it had seen reduced income from its Russian joint venture TNK-BP.

Its underlying replacement cost profit for the quarter - which pulls out the asset value reductions - fell to $3.7bn compared with $5.7bn a year earlier.

Shares in BP were down 3% in early trading in London.

Russian woes

BP chief executive Bob Dudley said: "We recognise this was a weak earnings quarter, driven by a combination of factors affecting both the sector and BP specifically."

The market and investors are still looking for a firm strategy from BP, and delivery on that strategyDavid Hunter, Analyst, M&C Energy Group

The company announced last month that it is to sell its 50% stake in TNK-BP. The move comes after it has endured a strained relationship with TNK-BP's other joint owner, Alfa-Access-Renova (AAR), a group of Russian billionaires.

Last year, BP had hoped to form a joint venture with Russia's largest oil firm, Rosneft, but this was abandoned after AAR launched a successful legal challenge.

A week ago, a Russian court ordered BP to pay $3.1bn in damages to minority shareholders in TNK-BP over the Rosneft affair. BP has said it will appeal.

In 2010, a BP oil rig exploded in the Gulf of Mexico, killing 11 workers and leaking four million barrels of oil. The company has now paid out a total of $38bn in compensation.

Mr Dudley said BP was continuing to turnaround its fortunes.

"Rebuilding trust with our shareholders and other stakeholders is vitally important," he said.

"We are making progress against the critical strategic and operational targets we have set ourselves, and are confident that this will deliver long-term, sustainable value."